RFID Tag Technology
Radio Frequency Identification (RFID) is an identification technology which relies on storing and retrieving data using devices called RFID tags. An RFID tag is in general a small object capable of functioning as a label, that can be attached to or incorporated into an item such as a commercial product, an animal, or a person.
Typically, an RFID tag consists of a small integrated circuit with a small storage capability and a radio antenna. Some tags, referred to as “active tags”, have an internal power source which is generally used to power any processing circuitry and to generate outgoing signals. Other tags, referred to as “passive tags”, do not have any internal power source. Passive tags generally obtain the energy required for responding to incoming signals and generating outgoing signals by collecting power from an electromagnetic field generated by a reader. Also, there exist tags known as “semi-active” (or sometimes “semi-passive”) tags, which generally have a small power source in order to enable the tag's processing circuitry to be powered constantly. These tags therefore do not need to collect power from incoming signals before commencing any processing, allowing them generally to provide faster responses than passive tags, but active and semi-active tags are generally more expensive than passive tags.
An RFID tag generally holds identity information at least relating to an item with which it is associated. Current RFID tags typically offer a 96-bit identifier number that can be globally unique and addressable. Upon being queried by a reader, a tag generally responds with identity information which may point to a unique location in a database in which detailed information about the item may be stored. This may include product characteristics, data about the origin of the item, the identity of a manufacturer and other manufacturing details, pricing information, any appropriate expiry dates, etc.
RFID technology is thought to be a possible at least partial replacement for barcode technology, for which there exists a standard called the Universal Product Code (UPC). An RFID tag can provide an identification number, as can a barcode, but unlike barcodes, RFID tags can be read at a distance without a line-of-sight requirement, and without human intervention. Due to this and due to their small size, RFID tags can be placed in boxes with, or even inside consumer items, can be attached to clothes, and can be used in a wide variety of other applications.
RFID tag technologies have been in use for many years but major technology development has happened in the last few years in particular through the Auto-ID Center in collaboration with the MIT. An aim was to make RFID tag as simple as possible, with very small chips and a cost per tag of less than 0.1 US$. At this level, it is thought that RFID tags will realistically start to replace the barcodes presently used in relation to many consumer products, and economies of scale will then enable research into new applications. It is likely that the first tags of a sufficiently small size and having a low-enough cost for the above will be passive tags.
RFID Technology in the Detection and Prevention of Counterfeiting
One aspect in which RFID technology can immediately improve on barcode technology and other labelling systems based purely on visible markings is in the detection of dishonest labelling of products, thus helping to eliminate illegal markets based on fake goods such as counterfeit pharmaceutical products; pharmaceutical products and other perishable items that should have been taken off the market due to their age or “sell by” date; counterfeit fashion items such as clothing and jewellery; consumer electronics devices; and many other goods. While barcodes can essentially be simply photocopied, such that on being read or “scanned”, the copy will provide the same data as the original, RFID tags cannot be so easily copied. They cannot generally even be “scanned” without the correct hardware, and various levels and types of encoding and authentication techniques can be used to protect data stored on or associated with them. This feature, coupled with the unique product codes that can be associated with products by means of RFID tags, and electronic “pedigrees” that can be provided by distributed databases, generally makes it harder and more expensive to convincingly label counterfeit goods as if they are genuine.
Counterfeit or out-of-date pharmaceutical products in particular represent a major risk to consumer safety. The World Health Organization (WHO) has estimated that around 7-8 percent of drugs worldwide are counterfeit, and reports from some countries suggest that as much as half of those countries' drugs are counterfeit. Medical authorities such as the Federal Drug Administration (FDA) in the United States, who are entrusted by governments with securing the safety of pharmaceutical preparations, are already making serious attempts to combat such problems, and it has already been suggested that RFID technology could make the copying of pharmaceuticals more difficult or unprofitable. An FDA report: “Combating Counterfeit Drugs” published on the internet in February 2004 strongly advocates the use of RFID in the pharmaceuticals industry, and suggests assigning a unique number to each drug package, pallet, or case to record information about all transactions involving the product, thus providing an electronic “pedigree” from the point of manufacture to the point of dispensing. By monitoring the pedigree and the information produced by an RFID tag the drug purchaser will be able to verify immediately the drug's authenticity. The information can provide full visibility of the supply chain.
The market for anti-counterfeiting solutions is of course not limited to the medical sectors. Around seven percent of world trade is thought to be in counterfeit goods. The music, software and luxury goods industries suffer enormous losses due to product cloning. Other markets are also heavily affected: up to 10 percent of all car parts, and up to 12 percent of toys commercialised in Europe are thought to be cloned. The consequences for users include safety hazards, financial losses and bad product experience. For manufacturers, the situation is worse. Consequences include unjustified liability claims, negative impact on brand reputation, loss of revenue and negative impact on production and R&D.
There are several approaches to the use of identifiers as an anti-counterfeiting mechanism. We will briefly discuss two such approaches: using a unique identifier contained in an optical label with security properties (e.g. holograms); and using a unique identifier contained in an RFID tag.
The first approach depends on authenticating a specific product through a label or a hologram that cannot be easily copied. The prevention of counterfeiting of items such as currencies, passports, cheques, bank cards, credit cards, optical disks and the like can be addressed by associating the item with a label that has optical security properties, and encoding optical data decipherable only by optical means therein. The label can be manufactured with different optical properties. For example the label film can comprise multiple substrates, the different substrates having different colours and different optical properties. The image produced by the label can change depending on the viewing angle. The labels may be human-readable or readable only using a specific optical reader. A similar approach is to create labels that reflect light in different ways. A reflective label can be designed to reflect light radiation of predetermined wavelengths while substantially absorbing or transmitting light radiation of other predetermined wavelengths irradiating the same location on the label surface.
The following two patent publications relate to authentication of labels: U.S. Pat. No. 5,549,953 (Li) entitled “Optical Recording Media Having Optically-Variable Security Properties”; and U.S. Pat. No. 5,568,251 (Davies et al) entitled “Authenticating System”.
In more recent approaches, which use RFID as the anti-counterfeiting technology, the main idea is to use a unique ID number to authenticate a product. The unique ID can be used to create an electronic pedigree system that allows for an end-to-end view of the product life cycle. A pharmaceutical bottle or package may contain an RFID tag that generates a unique identifier. The identifier can be a number in plain text or may be encrypted. A solution proposed by VeriSign is based on a tag that incorporates a 1024-bit encryption key and uses the same encryption technology proposed by smart card solutions.
Recently pharmaceutical industries have created electronic drug pedigree systems that detail a pharmaceutical product's movement through the supply chain. The concept is that an RFID tag or a simple barcode can be used to track a specific product from the manufacturing facility to a wholesaler and then to a retailer. The pedigree system makes use of a specific data file that maintains specific data about each single item. This system appears capable of reducing the risk of counterfeit medicines being introduced into the supply chain. While thieves and counterfeiters often exploit any weak links between the factory and the wholesaler and between the wholesaler and the retailer, RFID solutions integrated with such a pedigree model can make it possible to track and verify medicines and goods at low cost and without unnecessary disruption of current supply-chain processes.
A White Paper released in November 2005 on the “Anti-Counterfeiting of Medicines” by the European Federation of Pharmaceutical Industries and Associations (EFPIA) discusses the above issue from the points of view of different stakeholders in the pharmaceutical supply chain, and suggests the establishment of a “track-and-trace” information system in order to ensure the transparency of the supply chain and to combat offenders. In terms of technology the suggestion is to base this system on a pan-European Barcode standard. It is proposed that this standard should be able to work on the basis of the EPC (Electronic Product Code) as this is also compatible with other barcoding standards and with RFID technology. Furthermore, for such a scheme to be adopted, it is said that the impact on the cost per package should be very low—the White Paper suggests that it should not be higher than 1 eurocent per individual package. This last consideration implies that anti-counterfeiting applications should preferably aim to use functionality that can be provided by passive RFID tags.
As has been explained above, the cloning of RFID tags is generally harder and more expensive than the copying of barcodes and other labels according to systems based on visible markings, but it is not impossible. With appropriate devices such as readers and blank tags, cloning a standard tag (for example an EPC Generation 2 tag) can be done in a matter of minutes. The reader simply reads the original tag then writes the collected information to a blank tag.
The cloning operation is much harder when proprietary tags are deployed and when specific “trigger” signals are applied to read the tag information. In this case the aim of an attacker generally is to “reverse-engineer” the trigger-response algorithm by which the tag functions. In some cases “trigger” signals can be detected by a malicious user and can then be used to access information on a protected tag. One way to do this is to “eavesdrop”, i.e. listen passively to signals from RFID tags and readers. Another way to do this is to perform active “interrogation” of the tag, using a series of different “trigger” signals. The success or failure of this approach may depend, amongst other factors, on the complexity of any encryption algorithm of the tag, and whether one-way functions are used or not.
A final class of attack is hardware reverse-engineering. In this case an attacker physically probes the tag using microscopes or radio emissions from the tag circuit.
Passive tags generally are more likely to be susceptible to the risks of cloning than active tags because in the absence of an internal power supply, their circuitry is generally less complex than that on active tags. This can result in them being easier to probe using microscopes, radio emissions or otherwise. It can also mean that any access control provided through a reading protocol is likely to be less secure than mechanisms such as “RSA” or elliptic curve cryptography used on active tags.
A paper entitled “Security and Privacy Aspects of Low-Cost Radio Frequency Identification Systems” by Stephen Weis et al (Security in Pervasive Computing, vol. 2802/2004, January 2004, pages 201-212) presents a brief description of RFID systems and their operation, and describes privacy and security risks and how they apply in relation to low-cost RFID devices. It describes a hash-lock scheme where a hash of the access key is used on a tag as a Meta-ID. A reader fetches this Meta-ID to look up the correct key which is passed to the tag, before the tag responds with the tag ID. This scheme is similar to those described above, and suffers from eavesdropping, reply attacks and tracking (since the Meta-ID is revealed to everyone).
A paper entitled “Hash-based Enhancement of Location Privacy for Radio-Frequency Identification Devices using Varying Identifiers” by Dirk Henrici et al (Proceedings of 2nd IEEE Annual Conference on Pervasive Computing . . . March 2004, pages 149-153) relates to RFID devices, and introduces a scheme relying on one-way hash-functions to enhance location privacy by changing traceable identifiers on every read. The ID is changed by a backend system, which communicates the change to the tag as the last communication to the tag. If this were to fail, the backend system and tag would be out of synchronisation.
A paper entitled “RFID: Verbraucherängste und Verbraucherschutz” by Oliver Berthold et al (Wirtschaftsinformatik no. 47, 2005, pages 422-430) discusses consumer fears and consumer protection in relation to RFID technology, explaining that it enables physical environments to become more interactive and supportive by tagging each item with a chip that wirelessly communicates with a service-enriched backend infrastructure. The paper presents the major fears associated with RFID introduction, discusses to what extent these fears are justified, and aims to derive some system requirements for giving users more control over an RFID-enabled IT infrastructure.
A paper entitled “Strengthening EPC Tags Against Cloning” by Ari Juels published online at http://portal.acm.org/citation.cfm?id=1080793.1080805 in September 2005 discusses techniques that may strengthen the resistance of EPC tags to elementary cloning attacks.
A paper entitled “Extending the EPC network: the potential of RFID in anti-counterfeiting” by Thorsten Staake et al (Procs. of 2005 ACM Symposium on Applied Computing, 17 Mar. 2005, pages 1607-1612) discusses how unique product identification numbers together with an infrastructure used to share RFID-related data over the Internet may provide a basis of efficient “Track & Trace” applications. The paper notes that the EPC Network can be used to provide pedigree information of products and makes plausibility checks possible, and proposes a solution for products requiring authentication mechanisms that go beyond track & trace.